Non-diffusing inhibitors of formaldehyde hardening



to swelling by water.

sometimes used which may release formaldehyde.

United States Patent Ofifice 3,314,793 NON-DIFFUSENG INHIBITORS OF FORM-ALDEHYDE HARDENING Kenneth C. Kennard and Hyman L. Cohen, Rochester,N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporationof New Jersey No Drawing. Filed Dec. 27, 1962, Ser. No. 247,524 8Claims. (Cl. 96-83) This invention relates to gelatin compositionscontaining non-diifusing inhibitors of hardening by formaldehyde whichare polymers containing a hydrocarbon backbone and having a group likeas a substituent therein.

In the use of gelatin particularly for photographic products (forforming layers therein formaldehyde has been added to increase theresistance of the gelatin layer Formaldehyde has been found to actrapidly and eificiently for this purpose. However, formaldehyde as ahardener has the disadvantage that it will migrate from the layer inwhich it has been incorporated to adjacent layers. This has been foundundesirable in photographic products having a plurality of gelatinlayers, some of which layers should be hardened and others retained in anon-hardened condition. This is particularly true in products for use inphotographic products which depend on the stripping of one layer fromanother. Also in paper manufacture, sizing materials are When gelatinlayers are applied to paper of this nature there is the danger ofmigration of formaldehyde from the paper base to gelatin layers appliedthereover.

One object of our invention is to provide gelatin compositions in whichthe hardening effect of formaldehyde which migrates thereto isinhibited. Another object of our invention is to provide gelatincompositions containing polymeric materials which will inhibit thehardening effect of formaldehyde on the gelatin therein which materialswill not diffuse or migrate therefrom to other adjacent layers. Afurther object of our invention is to provide photographic productshaving gelatin layers hardened by means of formaldehyde plus otherlayers in less hardened or unhardened condition. A still further objectof our invention is to provide gelatin compositions which containpolymeric materials composed of a hydrocarbon backbone and having or thelike as a substituent group therein. Other objects of our invention willappear herein.

We have found that gelatin compositions containing polymeric materialshaving a hydrocarbon backbone and a substituent R2 -C-I| l-ITRa (i R.group, R R and R being hydrogen, alkyl, hydroxyalkyl and the like, nosubstituent having more than carbon atoms, will resist or partiallyresist the hardening effects of formaldehyde. We have found that thesegelatin compositions may be employed for the application of layers inphotographic products, which layers resist the hardening effect fromformaldehyde which might migrate thereto either from the use offormaldehyde as a hardener in an adjacent layer or from paper stock inwhich a formaldehyde releasing material has been used in the preparationof the paper. We have found that photo- 3,314,793 Patented Apr. 18,11967 graphic products may be prepared having a plurality of layers on asupport in which the gelatin layers containing polymeric materials asdefined herein remain in an unhardened condition even thoughformaldehyde or formaldehyde-forming compounds are present in adjacentlayers. We have found that by incorporating certain polymeric materialsin gelatin layers the use of formaldehyde as a hardener for gelatin inadjacent. layers is made possible without experiencing any hardeningeffect upon the gelatin layers in which the certain polymers have beenincorporated. We have found that by the use of lesser amounts of thepolymeric material the hardening effect of formaldehyde may be lessened,in cases Where complete resistance to formaldehyde hardening is notdesired.

In its broadest aspects our invention comprises gelatin compositionscontaining polymers having a hydrocarbon backbone and a substituent R1being hydrogen, alkyl, hydroxyalkyl and the like, no substituent havingmore than 20 carbon atoms. Our invention includes gelatin layerscontaining these materials and photographic products composed of layerscontaining formaldehyde or formaldehyde-forming compounds and gelatinlayers in which polymeric materials having a hydrocarbon backbone and-lC|1lTT-l T-R:|

0 R as a substituent group are present therein.

Polymeric materials having a hydrocarbon backbone and a substituentgroup, R R and R group, R R and R being hydrogen, alkyl, hydroxyalkyland the like, no substituent having more than 20 carbon atoms, adaptedfor use in preparing compositions in accordance with our invention areillustrated by the following compounds WhlCh have been found to beuseful for preparing gelatin coating compositions and gelatin layers:poly(4-vinylsemicarbazide), poly(acrylic hydrazide), copoly(vinylacetate-maleic hydrazide), poly- (vinyl-N-carbhydrazoyl methylcarbamate), poly(acry1ic semicarbazide), poly( lmethyl-4-vinylsemicarbazide) and poly(l-beta-hydroxyethyl-4-vinyl semicarbazide).These compounds when present in any proportion in a gelatin compositionexhibit an inhibiting effect against hardening by formaldehyde. The mostconvenient proportions however are those found Within the range of 2-20%based on the Weight of the gelatin.

Gelatin compositions in accordance with our invention (1) may be used ascarriers for silver halide in photographic emulsions such as where aphotographic product having an unhardened emulsion layer is desired, (2)they may be used for the application of intermediate layers especiallyas a stripping layer for products employed in photographic processesinvolving the stripping of one layer from another, (3) they may beemployed as the carrier for baryta in applying a baryta coating topaper, or (4) Where a controlled lesser degree of hardening is desiredaccomplished by the use in the gelatin composition of a diminishedamount of the inhibitor. The gelatin compositions in accordance with ourinvention are useful in any connection where an unhardened gelatin layeris desirable. As the inhibitors in accordance with our invention do notmigrate from the layer in which they were incorporated to adjacentlayers compositions in accordance with our invention make possible thepresence of formaldehyde hardened gelatin layers and unhardened gelatinlayers in immediate contact with each other.

The following examples are of procedures for preparing inhibitors offormaldehyde hardening which are useful in preparing compositions inaccordance with our invention:

Example 1 A solution of 268 grams of phenol in 375 ml. of dry ether wasadded dropwise over a period of one half hour to a stirred solution of178 grams of vinyl isocyanate in 500 ml. of dry ether keeping thetemperature at between 6 and 12 C. with external cooling. Followingaddition, the mixture was stored overnight in the refrigerator. Thesolution was then washed with 600 ml. of a sodium hydroxide solution,dried and the solvent evaporated under vacuum. The residual solid wasdissolved in a hot benzene ligroin solution and the mixture cooled. Theprecipitated solid was recrystallized from a benzene ligroin solutiongiving 315 grams of crystals in 75-76.

70 grams of these crystals (N-vinyl phenyl carbamate) and 350 mg. ofazobisisobutyronitrile were dissolved in 70 ml. of benzene and the masswas heated overnight on a 60 bath. The viscous solution obtained wasdiluted with acetone and precipitated in ether. Poly(N-vinyl phenylcarbamate) resulted in the form of a white powder.

32.6 grams of the poly(vinyl phenyl carbamate) thus obtained was mixedwith 64 grams of anhydrous hydrazine and 36 grams of water and the masswas stirred for 3 hours on a 60 bath. Solution was complete except for alittle gelatinous material. The solution was filtered and precipitatedin methanol. The precipitate was vacuum dried forming a white powder forpoly(vinyl semicarbazide).

Analysis.-C, 37.9%; H, 7.0%; N, 35.6%.

Example 2 Twenty grams of vinyl acetate-maleic anhydride interpolymerwere added with stirring to 300 ml. of hydrazine hydrate. The mass stoodfor 30 minutes at room temperature whereupon it was heated on a steambath for one hour. A smooth moderately viscous dope was obtained. Thisdope was cooled and poured in a fine stream into 3 liters of stirredabsolute ethyl alcohol which contained 30 ml. of 30% aqueous NaOH. Afriable precipitate was obtained. This precipitate was washed withalcohol and was redissolved in 150 ml. of distilled water. Added slowlyto this solution with stirring was 6 ml. of aqueous NaOH whereupon thesolution was poured into 2 liters of absolute alcohol containing 30%aqueous NaOH. The precipitate was extracted with absolute ethyl alcoholuntil free of alkali and was dried in a vacuum desiccator. The productwas the hydrazide of vinyl acetate-maleic anhydride interpolymer.

Example 3 21 grams of polymet-hyl acrylate, 96 grams of hydrazine and 54grams of water was stirred at 60 for 4 hours. Most of the soliddissolved. The mass was diluted to one liter with water, filtered anddialyzed. The material remaining in the cellulose casing was evaporatedto 300 ml. to contain 5% of solids. To obtain the dry product the masswas precipitated with methanol, and the precipitate was washed andvacuum dried to give dry polyacrylic hydrazide.

Example 4 A suspension was prepared of grams of poly(N-vinyl- O-tphenylcarbamate) in 46 grams of N-methyl-hydrazine. The mass was tumbledovernight and was then heated for 3 hours on a steam pot. It was cooled,precipitated in ether and the precipitate was washed and vacuum dried.There was thus obtained 7.5 grams of poly[(1-rnethyl-4-vinyl)semicarbazide] in the form of a white powder soluble in water.This material was found to be useful as an inhibitor of hardening ofgelatin by formaldehyde. Also it did not migrate when placed in layersof gelatin adjacent to other layers of gelatin or other colloidalmaterial.

Analysis.-C, 43.4%; H, 8.3%; N, 31.0%.

Example 5 10 .grams of poly(N-vinyl-O-phenyl' carbamate) was mixed with76 grams of beta-hydroxyethylhydrazine. The mass Was tumbled overnightforming a clear, very viscous solution. It was then heated for 3 hourson a 60 bath and the resulting mass was precipitated with n-propanol andthe precipitate formed was repeatedly washed with pr-opanol and vacuumdried. The polymer obtained was then dissolved in water, reprecipitatedin propanol and vacuum dried. 5 grams of poly[(1-beta-hydroxyethyl-4-vinyl)-semicarbazide], soluble in water and in methanol was obtained.

Example 6 A mixture of 54 grams of N-bromosuccinimide, 2.3 grams ofallyl chloride, 10 mg. of benzoyl peroxide and 500 ml. of chloroform wasrefluxed for 4 hours. After cooling the mixture, there was added theretoml. of anhydrous methanol dropwise with stirring causing an exothermicreaction. After this addition the mixture was refluxed overnight. Thesolvent was evaporated off by vacuum and the residue obtained wasrecrystallized with 200 ml. of methanol giving 40 grams ofN-(beta-bromoethyl)-O-methylcarba-m'ate. 21 grams of the carbamate soprepared was dissolved in 100 ml. of acetonitrile and 10.2 grams oftriethylamine was added thereto causing an exothermic reaction and themixture was allowed to stand for an hour and was then cooled whereuponcrystals separated. The crystals were filtered off and the filtrate waspoured into 500 ml. of ether. The precipitate thus formed was filteredoff. The filtrate was evaporated to dryness under vacuum. The residuethus obtained was dissolved in 100 ml. of benzene and the mixture wascooled togive 16 grams of crystals, melting at 138-140", forming acrylylmethyl carbamate.

A solution was prepared of 20 grams of N,N-dimethyl acrylamide, 26 gramsof acrylyl methyl carbamate and 0.5 gram of azobisisobutyronitrile in100 ml. of acetone. The solution was heated overnight on a 50 bath undernitrogen. By morning the mixture had solidified. The polymer formed wasdissolved in methanol and precipitated in ether which precipitate waswashed and vacuum dried giving a white fibrous solid.

A mixture of 15 grams of the product obtained namely copo-ly(N,N-dimethyl acrylamide-N-acrylyl-O-methyl carbamate) and 300 ml. ofhydrazine was tumbled overnight giving a clear, viscous solution. Themass was heated one hour in a 60 bath and the excess hydrazine was thenremoved under vacuum. The residue was dissolved in a mixture of 10 ml.of water and 200 ml. of methanol and was precipitated in ether. Theprecipitate was washed with isopropanol and dried. 13 grams ofcopoly(acrylyl semicarbazide-N,N-dimethyl lacrylamide) was obtained in aform of a white powder. This material was found to be a good inhibitorof gelatin hardening by formaldehyde and exhibited resistance tomigration from gelatin layers, in which it was incorporated, to adjacentcolloidal layers.

Analysis.-C, 46.6%; H, 7.8%; N, 22.8%.

The following examples illustrate the use of these inhibitors in gelatincompositions:

Example A To a high speed silver bromoiodide gelatin emulsionformaldehyde was added. Nondiffusing inhibitor (polyacrylic hydrazide)as an aqueous solution, was added thereto just before coating. Thisemulsion was coated on a cellulose acetate support at a coverage of 1040mg.

"ofge latin per square foot and 460 nrg.'of silver per square foot. Asample of each coating was exposed on an Eastman Ib'sensitometer,processed in Kodak DK-SO developer, fined, washed, and dried. The testsof the various products including those without both formaldehyde and ii Example D Procedure similar to that described in the precedingparagraphs was carried out using as the inhibitor poly(vinyl-N-carbhydrazoyl methyl carbamate). The results were as follows:

Percent of Vertical Swell inhibitor and those excluding one or the othergave the following results:

We claim: 1. A photographic product comprising a support con- Percent ofD escriptiou Speed 7 Fog Vertical Swell Control. 100 1.07 .11 658 HCHO,.1% on wt. gel 78 93 11 558 HCHO, 3% on wt. gel. 74 80 .09 264 HCHO, .6%on wt. gel 68 73 .08 206 P01y(aerylic hydrazide), 2.04% on wt. gel- 13298 16 696 #2 +#5 132 98 12 644 #3 +#5- 129 1. 02 12 609 #4 #5 118 92 11400 123 88 29 454 126 90 26 40B 110 92 37 590 123 .88 .28 575 Example BA similar procedure was employed as in the preceding paragraph exceptthat copoly(vinyl acetate-maleic hydrazide) was used as the inhibitor.The results obtained were as follows:

0 taining thereon a gelatin layer having formaldehyde and adjacentthereto a non-hardened gelatin layer containing therein a formaldehydehardening inhibitor comprising Percent of Description Speed '7 FogVertical Swell 7- Cop01y(vinyl acetate-maleic hydrazide), 102 1.00 14989 4.08% on wt. g

a hydrocarbon backbone and Example C as a substituent group thereon: 60O R A similar procedure was used but poly(4v1ny1 semi- N 2 carbazide)was employed as the inhibitor. The results were as follows:

Percent of Description Speed 7 Fog Vertical Swell 1 Control 100 1. 12659 2 HCHO, .5% on wt. gel 76 .87 .10 240 3.----- Polyvinylsemicarbazide 1% on wt. geL 110 1. 58 11 651 4 Polyvinyl semicarbazide5% on wt. gel.-. 110 1.41 10 574 5 Polyvinyl semicarhazide 10% on wt.gel 105 1. 11 554 6 #2 +#3 83 1.02 .10 257 7 1. 29 10 502 95 1. 32 10569 R R and R each being selected from the group consisting of hydrogenalkyl and hydroxyalkyl.

2. A photographic product comprising a support having thereon a gelatinlayer containing poly(4-vinyl semicarbazide) and thereover a silverhalide gelatin photographic emulsion layer containing formaldehydehardener.

3. A photographic product, some portion of which contains formaldehydeor a formaldehyde former, having therein a gelatin layer containing aformaldehyde hardening inhibitor comprising a polymeric material having10 a hydrocarbon backbone and as a snbstituent group thereon:

R Ja R R and R each being selected from the group co-nsist- 7 containsformaldehyde or a formaldehyde former, having therein a gelatin layercontaining as aformaldehyde hardening inhibitor copo-ly(vinylacetate-male'ic hydrazide )1 7. A photographic product, some portion ofwhich con- 5 tains formaldehyde or :1 formaldehyde former," havingtherein a gelatin layer containing as a formaldehyde hardening inhibitorpoly(vinyl-N-carbhydrazoyl methyl carbamate).

8. A photographic product, some portion of which contains fonmaldehydeor a formaldehyde former, having therein a gelatin-silver halidephotographic emulsion layer containing po-ly(4-vinyl s'emiearbazide).

References Cited by the Examiner 15 v UNITED STATES PATENTS 2,668,1542/1954 Orth 260-6 2,940,956 6/1960 Smith 96-114 3,168,400 2/1965Blackmer etal. 96-22 20 OTHER REFERENCES Kern et al.: Angew, Chem., vol.69, pp. 15371 (1957). Welzel et al.: Makromol. Chem, vol. 44-46; p p.2217 (1961).

NORMAN G. TORCHIN, Primary Examiner. I. T. BROWN, R. H. SMITH, AssistantExaminers.

3. A PHOTOGRAPHIC PRODUCT, SOME PORTION OF WHICH CONTAINS FORMALDEHYDEOR A FORMALDEHYDE FORMER, HAVING THEREIN A GELATIN LAYER CONTAINING AFORMALDEHYDE HARDENING INHIBITOR COMPRISING A POLYMERIC MATERIAL HAVINGA HYDROCARBON BACKBONE AND AS A SUBSTITUENT GROUP THEREON: